Avoid being alone
If you can not avoid, ask for help from someone you trust to accompany you. In this way, attention is divided among more than one person and you look at your colleague instead of your ex. Spend time with your loved ones. Go out with your friends, go to visit family members (other than the ones who praise your ex and say "how good was that guy" or "that girl was so nice"), and surround yourself with people who appreciate you. Do something as a group you like and generate good memories.
Make a list of goals
You'll be able to concentrate on things you want to achieve, rather than hold on negative feelings. In addition, it will force you to reevaluate things you wanted. Make a list of anything like travel, learning something or anything you like and this will help you in not thinking about your ex boyfriend or girlfriend.
It is always advised that if your anger is above normal or you think of hurting your ex then it is best you visit a psychologist or psychiatrist for helping you out with this situation. If you had a breakup few weeks back then remember it is normal to feel this hatred towards him/her. With time these feelings will get evaporated from your mind. So stay happy and move ahead in life as there are many guys and girls out there and one day you will find your soulmate.